DSMC112备件模块
总线终端系统
确保外部绝缘装置中的24 V馈线未连接到其中一个通信插座非常重要。如果它对24 V馈电没有100%绝缘，来自24 V侧0 V的干扰和接地电流将中断通信。使用这种类型的单元可以解决一个问题，但会产生更大的问题！不符合标准的安装现在可能有效，但连接其他设备时可能会出现问题。电缆和总线终端RS485•使用屏蔽双绞线电缆。如果要使用最大传输距离和最大传输速度，则对电容不得超过52.5 pF/m，面积至少为0.25 mm2（AWG 24）。•0 V，通信参考电压应包含在电缆中。双向通信使用两对；一对用于通信，一对用于0V。•屏蔽的一端必须接地。另一端通常接地，但如果距离较长或接地电位存在差异，则应通过0.1 uF/250 V塑料电容器将屏蔽连接至接地，以防止编织屏蔽中的接地电流。许多制造商建议屏蔽在每个节点接地。不同的制造商有不同的总线终端系统。RS485标准没有描述如何执行“故障保护”功能，只是系统应该能够处理错误
Bus terminal system
It is important to ensure that the 24 V feeder in the external insulation is not connected to one of the communication sockets. If it is not 100% insulated to the 24V feed, the interference and grounding current from the 24V side 0V will interrupt the communication. Using this type of unit can solve a problem, but it will create a bigger problem! A non-standard installation may now work, but problems may arise when connecting other devices. Cable and bus terminal RS485 • Use shielded twisted pair cable. If the maximum transmission distance and maximum transmission speed are to be used, the capacitance shall not exceed 52.5 pF/m and the area shall be at least 0.25 mm2 (AWG 24). • 0 V, the communication reference voltage shall be included in the cable. Two pairs are used for two-way communication; One pair for communication and one pair for 0V. • One end of the shield must be grounded. The other end is usually grounded, but if the distance is long or the ground potential is different, the shield should be connected to ground through a 0.1 uF/250 V plastic capacitor to prevent the ground current in the braided shield. Many manufacturers recommend that the shield be grounded at each node. Different manufacturers have different bus terminal systems. The RS485 standard does not describe how to perform the "fail safe" function, but the system should be able to handle errors
